Critic's Notebook: Seven seasons ago, Tina Fey unleashed '30 Rock' — so smart and self-aware — on the unsuspecting public. Now it's time to say good-bye, if we must.

I fell in love at first sight with Tina Fey's "30 Rock," the NBC sitcom that Thursday night will end our seven-season relationship with a double-length series finale. We have both grown in the interim — well, "30 Rock" has — and if it is not now the same series that first won my heart, by winning my head, it is an even better one, bold and confident and more completely itself.

The show that premiered on Oct. 11, 2006, was in many respects a conventional backstage comedy. Fey's show runner Liz Lemon struggled with corporate interference in the form of Alec Baldwin's Jack Donaghy, "the new vice president of East Coast television and microwave programming" — GE owned NBC at the time — and an unruly new star, Tracy Morgan's Tracy Jordan, who introduced himself to her letting her know that, contrary to tabloid reports, "I'm not on crack, I'm straight-up mentally ill."

At the same time, it contained the seeds of all it would become — as a comedy series on NBC about a comedy series on NBC, it was self-referential and meta-fictional from the start, and an unpredictable line like "We're a team now, like Batman and Robin, like chicken and a chicken container" (Tracy to Liz) signaled an original ear, a different sort of approach to a joke.

By the fifth episode, in which a product placement for Snapple was made brutally obvious and the fourth wall came down, the future was apparent: Anything was possible as long as it was done in character. From the invented swear words of Liz Lemon to the cast becoming Muppets to an episode that morphed into a "Dark Knight" movie, to a live episode and episodes framed as a reality show, "Why not?" became its guiding principle.

The humor was so unmistakably smart and self-aware that the writers could get away with the most sexist, racist or scatological remarks and still smell fresh: In its large and able cast, abetted by a league of recurring and guest players, there was a voice for every uncomfortable occasion — if each character had her or his own sort of intelligence, or survival instinct, each also had a special sort of stupidity.

Fey's original, rejected pitch had been for a show set at a cable news network to feature herself and Baldwin; she switched it back to more familiar territory and added Morgan — the "third heat," to borrow a phrase from the show — that allowed her to write about gender, race and class. Right off the bat, this distinguished the show's ambitions from those of nearly everything else on television.

They also formed a kind of group psyche, with Liz the ego and Jack the superego, with id Tracy doubled by Jane Krakowski's needy Jenna Maroney — a doubleness made explicit in a recent episode when the two were essentially reincarnated as the twins that Liz has adopted.

Paced and scored (marvelously, by Fey's husband, Jeff Richmond) with the moment-by-moment precision of a Tex Avery cartoon, "30 Rock" specialized in a kind of sudden-turn joke in which the end of a sentence could not be guessed from its beginning. (Jenna: "She's lying like a rug — rug is an offensive term for Persians that I made up." Tracy: "I once played a lawyer in a movie, so I know all about winning your son's love back, thanks to a magic camera.") Such turns came to be expected, but were no less pleasurable for it.

Fittingly, the final episodes of "30 Rock" are about the final episodes of the show within the show. They are full of returning characters and themes, nods small and large to the early episodes, and some last bites of the hands that fed them: "This is broadcast television — it's a nasty, ruthless business," Jack told Jack McBrayer's pure-to-the-last page Kenneth in last week's episode, as he looked to hire his own replacement, a dying enterprise in need of "a grave robber who'll strip every last bauble off the corpse."

At the same time, they provide many occasions to be moved, even as they mock the manipulative ways that television tries to move you. Because, underneath the irony and the parody and the satire, the knowingness and the cleverness and the strangeness, it's clear that the series was made with commitment and exhilaration, and that love, though it takes many unusual forms, has been its most constant themes. Just so, Fey has taken steps to send off her creations with their hearts' desire.